Scroll type compressor with displacement adjusting mechanism

Description

[0001] This invention relates to a compressor, and more particularly, to a scroll type compressor for an air conditioning apparatus which includes a mechanism for adjusting the displacement of the compressor.

[0002] Scroll type fluid displacement apparatus are well known in the prior art. For example, US-A-801,182 (Creux) discloses a device including two scrolls each having a circular end plate and a spiroidal or involute spiral element. These scrolls are maintained angularly and radially offset so that both spiral elements interfit to make a plurality of line contacts between their spiral curved surfaces to thereby seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scrolls shifts the line contact along the spiral curved surfaces and, as a result, the volume of the fluid pockets changes. Since the volume of the fluid pockets increases or decreases dependent on the direction of the orbital motion, the scroll type fluid apparatus is applicable to compress, expand or pump fluids.

[0003] Scroll type fluid displacement apparatus are suitable for use as refrigerant compressors in air conditions. In such air conditioners, thermal control in the room or control of the air conditioner is generally accomplished by intermittent operation of the compressor which in turn is activated or controlled by a signal from a thermostat located in the room being cooled. Once the temperature in the room has been cooled down to a desired temperature, the refrigerant capacity of the air conditioner for supplemental cooling because of further temperature changes in the room, or for keeping the room at the desired temperature, generally need not be very large. However, prior art air conditioners do not have capacity control mechanisms. Therefore, after the room had been cooled to the desired temperature, the manner for controlling the output of the compressor is by intermittent operation of the compressor. The relatively large load, which is required to drive the compressor, is thus intermittently applied to the driving source. When the compressor is used in an automotive air conditioner, it is driven by the engine of automobile through an electromagnetic clutch. Such prior art automotive air conditioners face the same output problem once the passenger compartment reaches a desired temperature. Control of the compressor's output is accomplished by intermittent operation of the compressor through a magnetic clutch which connects the automobile engine to the compressor. The relatively large load, which is required to drive the compressor, is thus intermittently applied to the automobile engine.

[0004] DE-A-2 338 808 discloses a scroll-type compressor wherein an end plate of one scroll is formed with a series of holes, each of which is normally closed by a spring-loaded valve member. When the pressure of fluid within a pocket reaches a certain value, however, the valve member associated with that pocket is forced away from its hole and fluid flows via the hole to a discharge opening. EP-A-9350 also discloses a scroll-type compressor having a hole formed in an end plate of one scroll and a spring-loaded ball associated with the hole. The ball is moved away from the hole to allow outflow of fluid when the centrifugal force exerted thereon exceeds a certain value. In the compressors of DE-A-2 338 808 and EP-A-9350 the holes and associated valve members or balls serve to prevent an undue increase of pressure within the fluid pockets.

[0005] Our co-pending EP-A-43701 also discloses a scroll-type apparatus in which an end plate of a fixed scroll member is formed with a pair of holes for connecting respective fluid pockets to a low pressure fluid chamber. Associated with each hole is a valve member which normally closes the hole. Control means are provided for actuating the valve members.

[0006] It is a primary object of this invention to provide an improvement in a scroll type compressor by incorporating a mechanism for changing the compression ratio of the compressor as occasion demands without the loss of energy consumption.

[0007] It is another object of this invention to provide a scroll type compressor in which sealing of the fluid pockets is maintained while achieving the above object.

[0008] According to the present invention there is provided a scroll type compressor including a pair of scroll members each having an end plate and a wrap extending from one side surface of said end plate, said wraps interfitting at an angular and radial offset to make a plurality of line contacts between said wraps, thereby to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected to one of said scroll members for orbiting said one scroll member relatively to the other scroll member while preventing rotation of said one scroll member, thereby to change the volume of the fluid pockets, a first one of said end plates having a hole extending therethrough, and valve means for controlling the opening and closure of said hole, characterised in that at least one further hole extends through said first one of said end plates thus defining at least one pair of holes, said holes are so arranged as to connect a lower pressure space with respective fluid pockets which are newly-formed at an outer portion of said scroll members, a first one of said pair of holes opens adjacent to, and extends partially into the surface of, an inner side of the wall of the wrap which extends from said first end plate and is located at an angular position defined by

where <})g_nd is the final involute angle at which said first hole is located, the other one of said pair of holes opens adjacent to, and extends partially into the surface of, an outer side of the wall of the same wrap and is located at an involute angle of approximately (0,-ri, so that the other wrap simultaneously crosses over both of said pair of holes to simultaneously block both of said pair of holes, and said valve means are controlled so that when said valve means are open fluid in the outermost newly-formed pair of fluid pockets is permitted to flow back into the lower pressure space during an initial movement of the fluid pockets, compression only beginning when the pair of holes have been crossed by the other wrap and the pair of fluid pockets are sealed, the displacement volume thus being controlled by operation of the valve means.

[0009] One embodiment of the invention is a scroll type compressor including a pair of scrolls each having an end plate and a wrap extending from one side surface of the end plate. The wraps interfit at an angular and radial offset to make a plurality of line contacts and define at least one pair of sealed off fluid pockets. One of the scrolls (an orbiting scroll) is driven in orbital motion by the rotation of a drive shaft, while the rotation of the orbiting scroll is prevented. The fluid pockets shift along the spiral curved surface of the wrap to change the volume of the fluid pockets. One of the end plates has at least a pair of holes formed through it. The holes are so arranged that the wrap of the other scroll member simultaneously crosses over the holes. A first of the holes is placed within at an angular position defined by

where φend is the final involute angle of the wrap which extends from the end plate having the holes, and (p, is the involute angle at which the hole is located. A control device controls the opening and closing of the holes. The displacement volume of the fluid pockets is controlled by opening and closing the holes with the control device. When the holes are closed compression operates normally and the displacement volume is not changed. When the holes are opened by the control device, fluid in the sealed off pockets flows back into the suction chamber through the holes until the spiral element of the other scroll crosses over the holes. The displacement volume in the fluid pockets is thereby reduced, and compression starts at an intermediate stage.

[0010] The invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a vertical sectional view of a scroll type compressor unit according to an embodiment of this invention;

Fig. 2 is a front end view of the fixed scroll member used in the compressor of Fig. 1;

Fig. 3 is a sectional view of the spiral elements illustrating tme hole extending into one of the spiral elements;

Fig. 4 is a perspective view of a magnetic coil used in the compressor of Fig. 1;

Fig. 5 is a front end view of a snap ring used in the compressor of Fig. 1;

Fig. 6 is a front end view of a valve mechanism according to another embodiment of this invention; and

Fig. 7 is a sectional view of a control mechanism according to another embodiment of this invention; and

Figs. 8a-8c are schematic views illustrating the operation of volume changing mechanism utilizing a pair of holes.

[0011] Referring to Fig. 1, a refrigerant compressor in accordance with an embodiment of the present invention, in particular, a scroll type refrigerant compressor 1 is shown. The compressor 1 includes a compressor housing 10 having a front end plate 11 and a cup shaped casing 12 which is attached to an end surface of front end plate 11.

[0012] An opening 111 is formed in the center of front end plate 11 for the penetration or passage of a drive shaft 13. An annular projection 112 is formed in a rear end surface of front end plate member 11. Annular projection 112 faces cup shaped casing 12 and is concentric with opening 111. An outer peripheral surface of annular projection 112 extends into an inner wall of the opening of cup shaped casing 12. Cup shaped casing 12 is fixed on the rear end surface of front end plate 11 by a fastening device for example, bolts and nuts. The opening of cup shaped casing 12 is thus covered by front end plate 11. An 0-ring 14 is placed between the outer peripheral surface of annular projection 112 and the inner wall of the opening of cup shaped casing 12 to seal the mating surfaces of front end plate 11 and cup shaped casing 12.

[0013] Front end plate 11 has an annular sleeve 15 projecting from the front end surface thereof which surrounds drive shaft 13 and defines a shaft seal cavity. In the embodiment shown in Fig. 1, sleeve 15 is separate from end plate member 11. Therefore, sleeve 15 is fixed to the front end surface of front end plate 11 by screws 16. An 0- ring is placed between the end surface of front end plate 11 and the end surface of sleeve 15 to seal the mating surfaces of front end plate 11 and sleeve 15. Alternatively, sleeve 15 may be integral with front end plate 11.

[0014] Drive shaft 13 is rotatably supported by sleeve 15 through a bearing 18 located within the front end of sleeve 15. Drive shaft 13 has a disk 19 at its inner end which is rotatably supported by front end plate member 11 through a bearing 20 located within opening 111 of front end plate 11. A shaft seal assembly 21 is coupled to drive shaft 13 within the shaft seal cavity of sleeve 15.

[0015] A pulley 22 is rotatably supported by a bearing assembly 23 which is carried on the outer surface of sleeve 15. An electromagnetic coil 24 is fixed about the outer surface of sleeve 15 by a support plate 25 and is received in an annular cavity of pulley 22. An armature plate 26 is elastically supported on the outer end of drive shaft 13 which extends from sleeve 15. A magnetic clutch thus includes pulley 22 magnetic coil 24, and armature plate 26. In operation, drive shaft is driven by an external power source, for example the engine of an automobile, through a rotation transmitting device such as the magnetic clutch.

[0016] A fixed scroll 27, an orbiting scroll 28, a driving mechanism of orbiting scroll 28, and a rotation preventing mechanism for orbiting scroll 28 are located in an inner chamber of cup shaped casing 12.

[0017] Fixed scroll 27 includes a circular end plate 271, a wrap or spiral element 272 affixed to or extending from one side surface of end plate 271. A partition wall 273 axially projects from the opposite side surface of circular end plate 271. An axial end surface of partition wall 273 is seated against and connected to an inner surface of end plate portion 121 of cup shaped casing 12 by fasteners (not shown). Circular end plate 271 of fixed scroll member 27 partitions the inner chamber of cup shaped casing 12 into a first chamber 29 and a second chamber 30. A seal ring 31a a is placed between the outer peripheral surface of end plate 271 and the inner wall of cup shaped casing 12 to form a seal between the mating surfaces. Spiral element 272 of fixed scroll member 27 is located within first chamber 29 and partition wall 273 is located within second chamber 30. Partition wall 273 further divides second chamber 30 into a suction chamber 301 and a discharge chamber 302.

[0018] Orbiting scroll 28 is located in first chamber 29 and also includes a circular end plate 281 and a wrap or spiral element 282 affixed to or extending from one side surface of end plate 281. Spiral elements 272 and 282 interfit at an angular offset of 180° and a predetermined radial offset. At least a pair of sealed off fluid pockets are thereby defined between the spiral elements 272 and 282.

[0019] Orbiting scroll 28 is rotatably supported by a bushing 31 through a bearing placed on the outer peripheral surface of bushing 31. Bushing 31 is connected to an inner end of disk 19 at a point radially offset or eccentric of the axis of drive shaft 13.

[0020] A rotation preventing/thrust bearing device 33 is placed between the inner end surface of front end plate 11 and the end surface of end plate 281 which faces the inner end surface of front end plate 11. Rotation preventing/thrust bearing device 33 includes a fixed ring 331 attached to the inner end surface of front end plate member 11, an orbiting ring 332 attached to the end surface of end plate 281, and a plurality of bearing elements, such as balls 333 placed between pockets 331a, 332a through rings 331 and 332. The rotation of orbiting scroll 28 during its orbital motion is prevented by the interaction of balls 333 with rings 331, 332; and the axial thrust load from orbiting scroll 28 is supported on front end plate 11 through balls 333.

[0021] Cup shaped casing 12 has an inlet port 34 and outlet port 35 for connecting the compressor unit with an external fluid circuit. Fluid is introduced from the external circuit into suction chamber 301 through inlet port 34 and flows into chamber 29 through a connecting holeformed through end plate 271 at a position near its outer peripheral surface. The fluid in chamber 29 is taken into the fluid pockets formed between spiral elements 272 and 282. As orbiting scroll 28 orbits, the fluid in the fluid pockets moves to the center of spiral elements and is compressed. The compressed fluid is discharged into discharge chamber 302 from the fluid pockets in the general area of the center of the spiral elements through a hole 274 formed through circular end plate 271. The compressed fluid is then discharged to the external fluid circuit through outlet port 35.

[0022] In such operation, fluid is generally taken into the fluid pockets formed between spiral element 272 and 282 through two open spaces. Each open space is defined between the outer terminal end of one of the spiral elements and the outer wall surface of the other spiral element. The entrance to these open spaces sequentially open and close during the orbital motion of orbiting scroll 28. While the entrances to these open spaces remain open, fluid to be compressed flows into them, but no compression occurs. After the entrances to the open spaces close, the sealed off fluid pockets are formed, no additional fluid flows into the pockets, and compression begins. The location of the outer terminal end of each spiral element 272 and 282 is at the final involute angle, therefore, the location of these open spaces is directly related to the final involute angle.

[0023] Referring to Fig. 2, the final involute angle (cpend) at the end of spiral element 272 of fixed scroll member 27 is greater than 4n but less than 5n. At least one pair of holes 275 and 276 are formed in end plate 272 of fixed scroll 27 and are arranged so that an axial end surface of spiral element 282 of orbiting scroll member 28 simultaneously crosses over holes 275 and 276. Hole 275 communicates between suction chamber 301 and one of the fluid pockets A, and hole 276 communicates between suction chamber 301 and the other fluid pocket A'.

[0024] Hole 275 is placed at a position defined by the involute angle (p, and opens along the inner wall side of spiral element 272. Thus, φ₁, is the involute angle location of the first hole, which is nearest the final involute angle (f))end) at the end of spiral element 272. The other hole 276 is placed at a position defined by the involute angle (φ₁-π) and opens along the outer wall side of spiral element 272. The preferred area within which to place the first hole 275, as defined in involute angles, is given by

The other hole 276 is located further from φend, i.e. at φ₁-π.

[0025] Holes 275 and 276 are formed by drilling into end plate 271 from the side opposite from which spiral element 272 extends. Hole 275 is drilled at a position which overlaps with the inner wall of spiral element 272, so that a portion of the inner wall of spiral element 272 is removed, as shown in Fig. 3. Hole 276 is drilled at a position which overlaps the outer wall of spiral element 272 so that a portion of the outer wall of spiral element 272 is removed. This overlapping of hole 275 is shown in detail in Fig. 3. In this arrangement, the axial end surface of each spiral element is provided with a seal 36 which forms an axial seal between the spiral element and facing end plate. Each of the holes 275 and 276 is so positioned that it does not communicate with the adjacent fluid pockets on respective opposite sides of the spiral element 282 overlapping the holes. Accordingly, the two adjacent pockets cannot be connected together via one of the holes. This is accomplished by extending a portion of each hole into spiral element 272 with the result that seal 36 in spiral element 282 remains completely in contact with end plate 271 when spiral element 282 completely overlaps the holes, while the size of holes 275 and 276 are kept sufficiently large.

[0026] A control mechanism 37 is located in suction chamber 301 and connected to the outer peripheral surface of partition wall 273. Control mechanism 37 includes a valve member having a plurality of valve plates 371 which are attached to the end surface of end plate 271 at each hole 275 and 276, and an annular shaped electromagnetic coil 372 attached to the outer surface of partition wall 273.

[0027] Each valve plate 371 is made of a spring type magnetic material, and is attached to the end surface of end plate 271 by a fastener, such as a screw 38. Magnetic coil 372 is fitted into a groove 277 formed on the outer peripheral surface of partition wall 273, and is held therein against axial movement by a snap ring 39, as shown in Fig. 5. The inherent spring tendency of each valve plate 371 pushes it against the opening of a respective hole 275, 276 to thus close the opening of each hole. Valve plates 371 are controlled by the operation of magnetic coil 372. By activating coil 372 the valve plates 371 are bent away from the openings in holes 275 and 276. Deactivating coil 372 permits the valve plates to again seal the openings to the holes because of their inherent spring tendency.

[0028] Magnetic coil 372 is provided with contact portions 372a at its end surface facing the valve plates 371. When valve plates 371 are drawn away from holes 275 and 276 by magnetic coil 372, they contact portions 372a.

[0029] Figs. 6 and 7 illustrate another embodiment of the valve member. In this embodiment, the valve member is formed as an annular valve plate 371' which has an inherent spring property or tendency. Contact portions 371a' extend from the end surface of plate 371' opposite to magnetic coil 372 and serve as contact points with coil 372. Valve plate 371' is fixed on the end surface of end plate 271 by two screws (not shown) which pass through holes 371b' in valve plate 371'. Valve plate 371' is held in sealing contact against the openings of holes 275 and 276 by its inherent spring property. However, when coil 372 is energized, valve plate 371' bends against its inherent spring property and holes 275 and 276 open.

[0030] Referring to Fig. 8, the operation of the mechanism for changing the displacement volume of the fluid pockets, i.e., the volume of the sealed off fluid pockets at the time compression begins, will be described.

[0031] When, during orbital motion, the terminal end portion of both spiral elements 272, 282 are in contact with the opposite side wall of the other spiral element pair of fluid pockets A, A' are sealed off and simultaneously formed at symmetrical locations as shown in Fig. 8a. If holes 275 and 276 are closed by valve member 371, compression of the fluid taken into the fluid pockets through the open space between the spiral elements begins. The fluid in the fluid pockets moves to the center of spiral element with the resultant volume reduction and compression, and is discharged into discharge chamber 302 through hole 274. In this operative mode, compression operates normally and the displacement volume of sealed off fluid pockets is determined when the terminal ends of the spiral elements first contact the other spiral element.

[0032] When valve member 371 is attracted to magnetic coil 372 by its activation, each hole 275 and 276 is opened. Thus, even though sealed off fluid pockets have been formed by contact of the terminal ends of the spiral elements with the opposite spiral elements, fluid which has been taken into the sealed off fluid pockets leaks from the sealed off fluid pockets A, A' back to suction chamber 301 during the orbital motion of orbiting scroll 28 from the position shown in Fig. 8a to the position shown in Fig. 8b. During this leaking or back flow, compression can not begin. This leaking continues until the axial end surface of spiral element 282 of orbiting scroll 28 crosses over and closes holes 275 and 276, this state being shown in Fig. 8c. As a result, the actial compression stroke of fluid pockets A, A' starts after the spiral element 282 of orbiting scroll 28 crosses over two holes 275, 276. The volume of the fluid pockets A, . A' at the time when the pockets are sealed from the suction chamber 301 and compression actually begins, is thereby reduced. In this manner, the capacity of the compressor is reduced.

[0033] In the preferred embodiment, the involute angle location of first hole 275 is given by

The closer (p, is placed to φ_end-2π. the larger the reduction of the displacement volume, and conversely, the closer (p, is made to (P_end, the smaller the reduction in the displacement volume. If the reduction in displacement volume is made too small, excess compression capacity would remain for conditions where only small temperature differentials are to be adjusted by the air conditioning system.

Claims

1. A scroll type compressor including a pair of scroll members (27, 28) each having an end plate (271, 281) and a wrap (272, 282) extending from one side surface of said end plate (271, 281), said wraps (272, 282) interfitting at an angular and radial offset to make a plurality of line contacts between said wraps (272, 282), thereby to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected to one of said scroll members (272, 282) for orbiting said one scroll member (28) relatively to the other scroll member (27) while preventing rotation of said one scroll member (28), thereby to change the volume of the fluid pockets, a first one (271) of said end plates (271,281) having a hole extending therethrough, and valve means (37) for controlling the opening and closure of said hole, characterised in that at least one further hole (275, 276) extends through said first one (271) of said end plates (271, 281) thus defining at least one pair of holes (275, 276), said holes (275, 276) are so arranged as to connect a lower pressure space (301) with respective fluid pockets which are newly-formed at an outer portion of said scroll members (27, 28), a first one (275) of said pair of holes opens adjacent to, and extends partially into the surface of, an inner side of the wall of the wrap (272) which extends from said first end plate (271) and is located at an angular position defined by

where (p_end is the final involute angle of the same wrap (272) and φ₁ is the involute angle at which said first hole (275) is located, the other one (276) of said pair of holes opens adjacent to, and extends partially into the surface of, an outer side of the wall of the same wrap (27) and is located at an involute angle of approximately φ₁-π, so that the other wrap (282) simultaneously crosses over both of said pair of holes (275, 276) to simultaneously block both of said pair of holes (275, 276), and said valve means (37) are controlled so that when said valve means (37) are open fluid in the outermost newly-formed pair of fluid pockets is permitted to flow back into the lower pressure space (301) during an initial movement of the fluid pockets, compression only beginning when the pair of holes (275, 276) have been crossed by the other wrap (282) and the pair of fluid pockets are sealed, the displacement volume thus being controlled by operation of the valve means.

2. A scroll type compressor as claimed in claim 1, wherein said valve means (37) includes at least one valve member (371, 371') and an electromagnetic coil actuator (372), the valve member (371') or each valve member (371) being attached to the end surface of said first end plate (271) and covering the opening of each of said holes (275, 276) or an associated one of said holes (275,276), said electromagnetic coil (372) being supported adjacent said valve member (371, 371') so as to move said valve member (371, 371') toward and away from said end surface to open and close said holes (275, 276).

3. A scroll type compressor as claimed in claim 2, wherein said valve member (371) comprises separate flat plates (371) attached adjacent to respective holes (275, 276).

4. A scroll type compressor as claimed in claim 2, wherein said valve member (371') comprises an annular plate (371').

Ansprüche

1. Kompressor vom Spiraltyp mit einem Paar von Spiralen (27, 28), von denen jede eine Endplatte (271, 281) und ein Spiralelement (272, 282), welches sich von einer Seitenoberfläche der Endplatte (271, 281) erstreckt, aufweist, wobei die Spiralelemente (272, 282) mit einer winkelmäßigen und radialen Versetzung zum Herstellen einer Mehrzahl von Linienkontakten zwischen den Spiralelementen (272, 282) zum Abgrenzen von mindestens einem Paar von abgeschlossenen Fluidtaschen ineinandergreifen, einem betriebsmäßig mit einer der Spiralen (272, 282) verbundenen Antriebsmechanismus zum Umlaufenlassen einer der Spiralen (28) relativ zu der anderen Spirale (27), während die Rotation der einen Spirale (28) verhindert wird, wodurch das Volumen der Fluidtaschen verändert wird, wobei eine erste (271) der Endplatten (271, 281) ein sich durch sie hindurch erstreckendes Loch aufweist, und einer Ventilvorrichtung (37) zum Steuern des Öffnens und Schliessens des Loches, dadurch gekennzeichnet, daß wenigstens ein weiteres Loch (275, 276) sich durch die erste (271) der Endplatten (271, 281) erstreckt und somit mindestens ein Paar von Löchern (275, 276) abgrenzt, die Löcher (275, 276) so angeordnet sind, daß sie einen Raum (301) niedrigen Druckes mit entsprechenden Fluidtaschen verbinden, die an einem äusseren Bereich der Spiralen (27, 28) neu gebildet sind, ein erstes (275) des Paares von Löchern sich öffnet benachbart zu und sich teilweise hineinstreckt in die Oberfläche einer inneren Seite der Wand des Spiralelementes (272), die sich von der ersten Endplatte (271) erstreckt und in einer Winkelposition angeordnet ist, die definiert ist durch

wobei (p_end den letzten Evolventenwinkel des gleichen Spiralelementes (272) und φ₁ den Evolventenwinkel, bei dem das erste Loch (275) angeordnet ist, darstellt, das andere (276) des Paares von Löchern sich öffnet benachbart zu und sich teilweise erstreckt in die Oberfläche einer äußeren Seitenwand der gleichen Spirale (27) und bei einem Evolventenwinkel von ungefähr φ₁-π so angeordnet ist, daß das andere Spiralelement (282) gleichzeitig über beide des Paares von Löchern (275, 276) geht zum gleichzeitigen Sperren beider des Paares von Löchern (275, 276), und die Ventilvorrichtungen (37) so gesteuert werden, daß, wenn die Ventilvorrichtungen (37) offen sind, Fluid in dem äußersten, neu gebildeten Paar von Fluidtaschen zurückfliessen kann in den Raum (301) niedrigen Druckes während einer anfänglichen Bewegung der Fluidtaschen, wobei Kompression nur beginnt, wenn das Paar von Löchern (275, 276) von dem anderen Spiralement (282) überquert ist und die Fluidtaschen abgeschlossen sind, wobei das Verdrängungsvolumen somit durch die Tätigkeit der Ventilvorrichtung gesteuert wird.

2. Kompressor vom Spiraltyp nach Anspruch 1, in dem die Ventilvorrichtung (37) mindestens ein Ventilteil (371, 371') und einen elektromagnetischen Spulenversteller (372) aufweist, das Ventilteil (371') oder jedes Ventilteil (371) an der Endoberfläche der ersten Endplatte (271) angebracht ist und die Öffnung von jedem der Löcher (275, 276) oder ein zugeordnetes der Löcher (275, 276) abdeckt, die elektromagnetische Spule (372) benachbart zu dem Ventilteil (371, 371') so getragen wird, daß das Venteilteil (371, 371') zu der Endoberfläche und von der Endoberfläche weg zum Öffnen und Schließen der Löcher (275, 276) bewegt wird.

3. Kompressor vom Spiraltyp nach Anspruch 2, in dem das Ventilteil (371) getrennte, flache Platten (371) aufweist, die benachbart zu den entsprechenden Löchern (275, 276) angebracht sind.

4. Kompressor vom Spiraltyp nach Anspruch 2, worin das Venteilteil (371') eine ringförmige Platte (371') aufweist.

Revendications

1. Compresseur de type à volutes comprenant une paire d'éléments de volutes (27, 28) comportant chacun une plaque d'extrémité (271, 281) et un enroulement (272, 282) faisant saillie sur une surface latérale de la plaque d'extrémité (271, 281), ces enroulements (272, 282) s'emboîtant avec un décalage angulaire et radial pour former un certain nombre de lignes de contact entre les enroulements (272, 282), de manière à définit ainsi au moins une paire de poches à fluide étanches, un mécanisme d'entraînement relié en fonctionnement à l'un des éléments de volute (272, 282) pour produire le mouvement orbital de cet élément de volute (28) par rapport à l'autre élément de volute (27) tout en empêchant la rotation du premier élément de volute (28), ce qui permet de modifier le volume des poches à fluid, la première (271) des plaques d'extrémité (271, 281) étant percée d'un trou, et des moyens de soupape (37) permettant de commander l'ouverture et la fermeture de ce trou, compresseur caractérisé en ce qu'au moins un autre trou (275, 276) est percé dans la première (271) des plaques d'extrémité (271, 281) pour définir ainsi au moins une paire de trous (275, 276), ces trous (275, 276) étant disposés de manière à relier un espace basse pression (301) aux poches à fluide respectives qui sont nouvellement formées dans la partie extérieure des éléments de volute (27, 28), un premier (275) de cette paire de trous débouchant au voisinage, et pénétrant partiellement dans la surface, d'un côté intérieur de la paroi de l'enroulement (272) faisant saillie sur la première plaque d'extrémité (271) et se plaçant dans une position angulaire définie par

où φ_ext est l'angle de développante final de ce même enroulement (272), et où <1>, est l'angle de développante où se situe le premier trou (275), l'autre (276) de la paire de trous débouchant au voisinage, et pénétrant partiellement dans la surface, du côté extérieur de la paroi du même enroulement (27) et se plaçant à un angle de développante d'approximativement φ₁-π, de façon que l'autre enroulement (282) croise simultanément les deux trous de la paire de trous (275, 276) pour bloqueur simultanément les deux trous de cette paire (275, 276), et les moyens de soupape (37) étant commandés de façon que, lorsque ces moyens de soupape (37) sont ouverts, le fluide se trouvant dans la paire de poches à fluide nouvellement formée dans la partie située le plus à l'extérieur, puisse revenir dans l'espace basse pression (301) pendant un mouvement initial des poches à fluide, la compression ne commençant seulement que lorsque la paire de trous (275, 276) a été croisé par l'autre enroulement (282), et lorsque la paire de poches à fluide est fermée de manière étanche, le volume de déplacement étant ainsi commandé par le fonctionnement des moyens de soupape.

2. Compressur de type à volutes selon la revendication 1, caractérisé en ce que les moyens de soupape (37) comprennent au moins un élément de soupape (371, 371') et un organe de manoeuvre à bobine électromagnétique (372), l'élément de soupape (371') ou chaque élément de soupape (371) étant fixé à la surface d'extrémité de la première plaque d'extrémité (271) et recouvrant l'ouverture de chacun des trous (275, 276) ou de l'un associé de ces trous (275, 276), la bobine électromagnétique (372) étant montée au voisinage de l'élément de soupape (371, 371') de manière à déplacer cet élément de soupape (371, 371') pour le rapprocher et l'écarter de la surface d'extrémité, de manière à ouvrir et fermer les trous (275, 276).

3. Compresseur de type à volutes selon la revendication 2, caractérisé en ce que l'élément de soupape (371) comprend des plaques plates séparées (371) fixées au voisinage des trous correspondants (275, 276).

4. Compresseur de type à volutes selon la revendication 2, caractérisé en ce que l'élément de soupape (371') comprend une plaque annulaire (371').

Drawing